This invention broadly relates to a probe contacting with an electrode of an LSI (Large Scale Integration) or a bear chip as a semiconductor device. More specifically, this invention is directed to a probe structure suitable for inspecting the LSI or the bear chip, each having a narrow electrode pitch.
Conventionally, the probe is contacted with an external terminal electrode of the semiconductor device to be inspected thereby to obtain an electric contact between the semiconductor device and an inspection substrate, and thus, inspecting the semiconductor device.
As the above mentioned probe, use is made of a metal needle, a metal pin, a membrane sheet with a metal protrusion, a plated silicon whisker and so on.
A method using the metal needle is disclosed in U.S. Pat. No. 5,969,533 (hereinafter, will be referred to as a first prior art), a method using the membrane sheet with the metal protrusion is disclosed in Japanese Unexamined Patent Publication (A) No. Hei. 5-226430 or Japanese Unexamined Patent Publication (A) No. Hei. 5-243344 (hereinafter, will be referred to as a second prior art), and a method using the silicon whisker is disclosed in Japanese Unexamined Patent Publication (A) No. Hei. 11-190748 (hereinafter, will be referred to as a third prior art), respectively.
Hereinafter, description will be made about the above-mentioned prior arts.
First, description will be made about the first prior art with reference to FIG. 1. According to the first prior art, the probe is formed by processing the metal needle made of tungsten, thereby making a pitch narrow.
In a probe structure illustrated in FIG. 1, probe needles 28 each having a root diameter of 190 xcexcm are laminated with four stages, and a tip pitch of the probe is narrowed to 50 xcexcm by the use of a shielding plate 27, thus improving positioning accuracy.
Subsequently, description will be made about the second prior art with reference to FIG. 2. In the probe structure according the second prior art, a contact sheet with a metal protrusion (bump) is disposed in opposition to an external electrode of the semiconductor device. As a representative example of the second prior art, a probe card structure is illustrated in FIG. 2.
Referring to FIG. 2, an inspection circuit pattern and an electrode lead 30 are formed on one surface of a flexible insulating film 29. On the tip of the electrode lead 30, a metal protrusion 31 is formed in opposition to the external electrode 2 of the semiconductor device 1. The metal protrusion is contacted with an external terminal electrode 2 with such a structure.
Next, description will be made about the third prior art with reference to FIG. 3. In the probe structure according to the third prior art, a silicon single crystal is grown in a bar shape, and the grown single crystal is plated to thereby form a probe pin.
As illustrated in FIG. 3, wires are drawn out from a contactor substrate 32 with probe pins 3 by using a flexible substrate 33 so as to connect with the inspection substrate.
The aforementioned first prior art has the following problems because the probes are laminated with the four stages through the metal needles and the shielding plates.
First, it is extremely difficult to process the needle and the shielding plate and assemble for the inspection substrate, which results to high cost.
Second, even if the probes are laminated with the four stages, the pitch is equal to 50 xcexcm at most. Therefore, it is difficult to further narrow the pitch from the viewpoint of rigidity of the metal needle.
Third, the needle becomes long to thereby increase resistance thereof. Consequently, a signal delay is increased also so that it is difficult to obtain high frequency.
According the second prior art, the contact with the external electrode is performed by the metal protrusion. The metal protrusion is kept to a constant height or more not to contact with a circuit surface of the semiconductor device upon contacting. In consequence, the pitch of the metal protrusions is on the order of 60 xcexcm at least, and therefore it is difficult to make the pitch narrower.
The above-mentioned third prior art has the following problems because a pin material is formed by plating silicon.
First, a signal delay occurs under a high speed by a resistance increase of the pit itself.
Second the contact with the external electrode of the semiconductor device is carried out via the pin plated for a bar-like single silicon crystal, and the wire is flatly drawn out for the external by the use of the flexible substrate and the connector.
Consequently, the resistance is increased by increasing a wire length, and the signal delay takes place by the difference between the wire lengths.
Third, pressing is required to obtain a stable contact by eliminating warping of the inspection substrate as well as height variation of the external terminal electrodes of the semiconductor device. In this circumstance, in case where each variation becomes large, the pin is destroyed readily.
It is therefore an object of this invention to provide a probe which is capable of suitably inspecting a semiconductor device having a narrow pitch and a method of manufacturing the same.
According to one aspect of this invention, a probe is provided so as to obtain an electrical contact between a semiconductor device having a plurality of first electrodes as external terminals and an inspection substrate having a plurality of second electrodes so as to inspect the semiconductor device.
A first substrate has through holes formed at positions corresponding to the first electrodes. Probe pins are fixed in the through holes, each of the probe pins having a vertical shape. A second substrate has a rewiring layer for extending a pitch of the first electrodes and penetration electrodes for drawing out the first electrodes to a back surface. A contact is disposed between the penetration electrodes and the second electrodes and has conductivity and elasticity only in a vertical direction.
Herein, the probe pin may be made by a metal material having a spring characteristic. The contact may be an anisotropic conductive sheet.
Each of the first and second substrates is preferably a silicon substrate. The first silicon substrate may be covered with an insulating layer for insulating between the probe pins.
The probe pins are desirably disposed with the same space as the fist electrodes. Here, the rewiring layer and the penetration electrode serve as a drawing-out pattern for connecting the probe pins to the inspection substrate.
In this event, a pitch of the second electrodes is extended wider than the pitch of the first electrode, and the rewiring layer is drawn out so as to extend the pitch of the second electrode.
The probe pin and the penetration electrode may be offset with a distance predetermined for re-wiring. The contact may have a tip portion and may be made by burying metal fine lines into a material having elasticity, and the tip portion may be protruded from a surface of the contact.
In this case, the metal fine line preferably has a vertical shape. Alternatively, the metal fine line may be inclined obliquely. Instead, the metal fine line may have an S literature shape.
The contact may be made so as to have elasticity in shape by a metal fine line with a spring characteristic disposed in opposition to each of the second electrodes. The metal fine line preferably has a covering material with elasticity. Herein, a portion having the rewiring layer and the penetration electrode may be multi-layered.
More specifically, according to this invention, the structural body having the metal probe pin with the spring characteristic, the rewiring layer for extending the pitch, and the penetration electrode for drawing out to the back surface together is employed as the probe. Consequently, the resistance of the pin itself can be reduced, and the increase of the resistance generated by drawing out the wire can be suppressed at minimum. Thus, test can be carried out at a high speed.
Moreover, the thickness of the semiconductor device, the thickness of the external electrode, the warping of the inspection substrate, and the slope of the total device can be extremely reduced by combining with the anisotropic conductive sheet, thus obtaining a stable and accurate contact.